c语言读写文件操作 

 1 #include <stdio.h>
 2 #include <math.h>
 3 #include <stdlib.h>
 4 void writefile()
 5 {
 6     FILE *fp;
 7     fp = fopen("e://ss.txt","w+");
 8     if(fp == NULL)
 9     {
10         exit(0);
11     }
12     int i=2, a=100, flag=0,count = 0;
13     for (a=2;a<=1000;a++)
14     {
15         flag=0;
16         i= 2;
17         while (i<=sqrt(a))
18         {
19             if (a%i==0)
20             {
21                 flag=1;
22                 break;
23             }
24             i++;
25         }
26         if (flag==0)
27         {
28             count++;
29 //          printf("%5d",a);
30             fprintf(fp,"%5d",a);
31             if(count % 10 == 0)
32             {
33 //                printf("\n");
34                 fprintf(fp,"\n");
35             }
36         }
37     }
38     fclose(fp);
39 }
40 void readfile()
41 {
42     char str[1024];
43     FILE *fp;
44     fp = fopen("e://ss.txt","r");
45     if(fp == NULL)
46     {
47         exit(0);
48     }
49     while(!feof(fp))
50     {
51         fgets(str,1024,fp);
52         printf("%s", str);
53     }
54     printf("\n");
55     fclose(fp);
56 }
57 int main()
58 {
59     writefile();
60     readfile();
61     return 0;
62 }

 

posted on 2014-11-05 15:37  嘘寒问暖  阅读(170)  评论(0)    收藏  举报

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